      SUBROUTINE J1CAL(J1,SUM,YYDB,BDYMI,ISO)
C
C     'J1CAL' CALCULATES THE TOTAL MOMENT OF INERTIA OF THE SATELLITE IN
C     THE BODY FRAME
C
      IMPLICIT REAL*8 (A-H,O-Z)
      REAL*8 ISO(3,3),J1(3,3)
C
      DIMENSION SUM(6),YYDB(3,3),BDYMI(3,3)
C
C
      ISO(1,1)=BDYMI(1,1) + SUM(1) + YYDB(2,2) + YYDB(3,3)
      ISO(2,2)=BDYMI(2,2) + SUM(2) + YYDB(1,1) + YYDB(3,3)
      ISO(3,3)=BDYMI(3,3) + SUM(3) + YYDB(1,1) + YYDB(2,2)
C
      ISO(1,2)=BDYMI(1,2) + SUM(4) + YYDB(1,2)
      ISO(1,3)=BDYMI(1,3) + SUM(5) + YYDB(1,3)
      ISO(2,3)=BDYMI(2,3) + SUM(6) + YYDB(2,3)
C
      ISO(2,1)=ISO(1,2)
      ISO(3,1)=ISO(1,3)
      ISO(3,2)=ISO(2,3)
C
      DO 10 I=1,3
      J1(I,I)=ISO(I,I)
      DO 10 J=1,3
   10 IF(I.NE.J) J1(I,J)=-ISO(I,J)
      RETURN
      END
